You can change the button you need to hold by editing the ini file. As well as adjust the sensitivity.
You can find a list of keycodes here:http://msdn.microsoft.com/en-us/library/windows/desktop/dd375731(v=vs.85).aspx
So to have it as the right mouse buttons you would have "key=2" in the ini file.
I'm currently woking on a UI to change these settings.
Anyone have any thoughts on a default for the reset camera button?
As for missing bit of the map, i've noticed a few here and there but it's generally not too bad. When someone from Runic posted that they were "optomising" it by removing things you would never normally see I was kind of worried that the game would be unplayable. I played far too much Dungeon Siege to go back to a fixed camera.